How Melanin Can Hurt Us

That energy can cause DNA lesions, which can lead to
cancer-causing mutations. The lesions typically appear less than one second after
UV radiation exposure.

The researchers noted, however, that particular damage can also
take place more than three hours after exposure to UVA radiation, which comes
from the sun and from tanning beds.

You’ve got this race going on between melanin blocking and protecting you.

Dr. Doug E. Brash, Yale School of Medicine

“You have two opposing things happening at the same time:
Melanin protecting you and melanin damaging you,” explained Dr. Doug E. Brash,
a skin cancer researcher at the Yale School of Medicine. “You’ve got this race
going on between melanin blocking and protecting you.”

Brash said
it is a simultaneous event — melanin protects us at the same time sunlight is
trying to damage our cells.

“A consequence of these events is that melanin may be carcinogenic
as well as protective against cancer,” the new report stated.

Examining Melanin in the Dark

In the study, researchers exposed mouse and human melanocyte
cells to UV radiation using a UV lamp. It led to cyclobutane pyrimidine
dimers
(CPDs), a type of DNA damage.

The melanocytes produced CPDs immediately and continued to
do so hours after UV exposure ended. Cells without melanin generated CPDs but
only during exposure to UV radiation.

"If you look inside adult skin, melanin does protect against CPDs. It
does act as a shield," Brash said in a statement. "But it is doing
both good and bad things."

Next, the scientists looked at the damage after sun exposure. They prevented
normal DNA repair in mouse skin samples and found that half of the CPDs in
melanocytes were created in the dark.

Another researcher learned that the UV light activated two enzymes that came
together to “excite” an electron in melanin. That energy, which is dubbed
chemiexcitation, was delivered to DNA in the dark. It created the same DNA
damage that sunlight caused in daytime.

Protecting Our Skin Inside and Outside

When we put on sunscreen during UV light exposure, it can
stop the risk of sun damage.

After we leave the beach or the tanning bed, however, any
exposure to UV radiation can still cause this harmful reaction with melanin.

Brash’s team is looking to create a product that could
suppress the reaction. It would be like an “evening after” sunscreen. People
could apply it like they would a moisturizer when they come in from the sun.

I think it’s still true that it’s best not go in the sun between 10 a.m. and 2 p.m.

Dr. Doug E. Brash, Yale School of Medicine

“Hopefully we can come up with a way to intervene,” Brash
said.

In the meantime, be careful with UV exposure, Brash warned.

“I think it’s still true that it’s best not to go in the sun
between 10 a.m. and 2 p.m.,” he said. “Just be reasonable.”